1. Field of the Invention
The present invention concerns a device for the regulation of a continuously variable transmission in motor vehicles.
2. Description of the Related Art
As is known, continuously variable transmissions consist of two V-shaped pulleys in between which a V-belt has been applied. Both pulleys are hereby formed of two cone-shaped pulley halves which can move in relation to one another, such that the transmission ratio can be altered by axially shifting the pulley halves of at least one of said pulleys either more or less apart, as a result of which the radius of the belt is altered. The mutual position of the pulley halves is adjusted as a function of different data, by means of hydraulic regulating means which are controlled by electronically driven control valves thereby providing for the moving of one of the pulley halves.
In order to make the continuously variable transmission work smoothly, it is desirable that the movement of the valve body of the main valve, which allows for the supply and discharge of the hydraulic medium to the regulating cylinder of the continuously variable transmission, is regulated by means of a control valve. Embodiments are known in which the valve body of the control valve is electromagnetically driven. These devices are disadvantageous however in that they are relatively complicated and expensive.